Nowadays, global connectivity leads to a tremendous creation of data and urges the need for Real-Time Systems (RTS). These systems refer to any information processing systems with hardware and software components that perform real-time tasks, i.e. within specific time constraints. They are used in a wide variety of applications, such as connected vehicles, smart homes, e-health, or the so-called Industry 4.0. They bring enormous opportunities to improve our lives, but also huge risks, in terms of security. However, the literature neglected the time-aware security in periodic task-based RTS, despite time being a crucial factor impacting their security. Therefore, we propose in this article, a clock-based modeling language and a toolchain called Sock, that allow developers to design and execute periodic task-based RTS, and reason over them. Sock is implemented as a set of Eclipse plugins using the GEMOC Studio, which yields generic components to develop and use executable modeling languages. We specify the operational semantics of Sock in terms of finite state machines, using logical clocks associated with tasks and resources' operations. To evaluate Sock, we implement two time-dependent attacks from the state-of-the-art, and we execute them on Sock models. We show that Sock helps engineers to avoid sensitive information leakage and alerts them to potential threats to the RTS systems.